Submerged-channel induction furnace



Sept. 18, l1928.

E. F. NoRTHRuP suusnsn CHANNEL mDucTIoN YFurman 2 Sheets-Sheet 1 vskilled in the art in Patented Sept. 18, 1928.

UNITED STATES PATENT oFFICE..

EDWIN F. NORTHRUP, 0F PRINCETON, NEW JERSJEY, ASSIGNOR TO Til-IE AJAX METAL I(Oll/LPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENNSYL- VAN IA.

sUBMERGEn-CIANNEL INDUCTION FURNACE.

Application filed August 1, 1925. Serial No. $17,593.

The purpose ofniy invention is to provide submerged molten resistors for induction electric furnaces, which shall have good heating capacity and adaptability to diiferent metals and alloys, and which at the same time shall be heffective yto secure good circulation of the molten metal.

A purpose of myinvention is to stagger the two parts of a channel which lie on opposite sides of the central transformer leg laterally with respect to the winding, whether a central core winding or pancake side winding be used.

A further purpose isto stagger the top and bottom of a L7resistor channel laterally with respect to the winding whether with an enclosed core winding or with pancake coils.

\ A further purposev is to form a channel in which the variant distances between the middle portions of upwardly anddownwardly extending limbs at corresponding sections of the Jlimbs is different from the distances between their edges.

l Further purposes will appear in the specication and in the claims.

I have preferred to illustrate my invention by a number of different' forms, and recognize that a great many additional forms of my invention will appear to those View of my disclosure herewith.

I have selected the forms shown among vthe larger number, therefore, withv a View to illustrating the principles thereof to best advantage by practical construction by which the principles may be applied.-

Figure l is a top plan view lof one form ofmy invention showing a double channel.

Figure 2 is a` section of Figure 1, taken Figure 3 is a section of Figure 2, taken upon line 3-3 thereof.

Figure 4 is a front elevation of the structure of Figure l.

Figure 5 I is a vertical section of a second form.

Figure 6 'is a. top` plan View of a third form ofmy invention. l

Figure 7 is a section of Figure 6, taken .upon line 7-7 thereof.

Figures 8, 9, 10, 11, 12 and 13 are sections I have shown corresponding to` line 8---8 of .Figure 7, showing different cross sections fof the channel passage, which may be used in the form olf' Figure 6, or for any of the channels shown in the other figures.

Figure 14 is a top plan view of a fourth general form of my invention.

Figure 15 is a section of Figure 14, taken upon line 15-15 thereof.

Figures 16 and 17 aresections of Figure 15, taken upon lines 16-16 and 17-17 thereof. I I Figures 18, to 26 inclusive are cross sections corresponding in position with section line 17-17, showing' suggested Yforms of cross section of channel opening fog use with pancake windings, double pancake'windings being shown in Figures 18 and 23 inclusive,I

yform, the view correspondingwiththat of Figures 2, 5, 7 and 15.

In the drawings similarnumerals indicateA likeparts. .4 o

illustrations based upon several diil'erent principles byv which 'circulation is secured.

Taking .up the several figures, and explaining them in illustration and not in limitation l v In Figures 1' to 4, a double staggered form of channel is shown which may be compared with the staggered single channel shown in Figure 13, diitering from it in having two of thesey staggered channels reversely sloping and communicating at thebottom;

A Crucible 30 is-shown, having pool space 31, usual pouring spout 32 and metallic sup* porting casing 33, v.suitably interrupted for convenience of insertion, if the Crucible be separately formed, or for ramming if the ma- -otherwise be the case.

40 and 41 of channel 3,8, and legs 42 and 43 o'fchannel 39. 'Ihe legs of these staggered channels meet at the bottom in a relatively sharp angle 44 so that the parts of the channel about the angle react upon each other to secure motor eifect drive up the outsides of the channel, with gravity return down the insides of thel channel as in Vyatt Patent No. 1,201,671. There is also some attraction of the currents flowing in the saine direction in thc diverging paths shown, as discussed in Wyatt Patent No. 1,312,069, in connection with Figures 10-12. y

The lateral staggering of the channels-results'in a difference in pressure laterally (parallel to the axis of the winding) at the bottom with respect to the top, due to reaction ot primary on secondary in their entireties, so as to vary, the iiow, causing the metal to low up somewhat more along the out-er lateral sides of the channel than would These several forces will of course be. proportioned by the designer according to the character of circulation sought.

The character of circulation obtained will be that of the dominating torce, causing circulation slightly modified by the other forces indicated, i. e., the path will be cleared and the metal will be moved forcibly by the dominating circulation and that flow due to other causes will combine with it, slightly modifying its position, but without substantial modification of its general direction.

At the top of the channels the floor of the pool is grooved as seen in solid lines in Figure 1, and as shown by the space 45, in Figure 2, the grooving extending downwardly along curved lines as shown at 46 in Figure 2. Y ,A

Cgnvenient trunnion supports are shown at l In Figure 5 the illustration is intended to be substantially the same as in Figures 1-4,

except that the lower portion of the channel is curved-instead of. being extendedi downwardly along straight sides to an angle, the curvature of the lower portion at 48 being shown as concentric with the transformer leg and winding; The two staggered channels come together at the bottom at 44. Here reliance for circulation is placed upon lateral staggering of the channel portions with respect to the winding and upon pinch pressure, present in all such channels.

In Figures 6, 7 and 8 the single channel 49 is not laterally sta gered, but the outer lateral edges 50 are c oser to the winding than the central portion 51, with the result that the reaction of secondary upon secondary, producing motor effect drive, greatest at the point 1,201,671, is assisted by the reaction'of primary upon secondary, causing a greater 44 as in the vWyatt Patent, No.

channel, with la relatively largerA flow downwardly along the outer edges of the channel.

In the form shown in Figure 9 the middle of i the channel 51, considered laterally, is nearer to the winding than outer edges 50,

resulting in just the reverse of the distortion` of iiow takingvplace in the form of Figures 6,-8. As a resultthe greater flow is up along the outer edges and down along the middle portion ot the channel.

In the sections in Figures 6, 8 and 9 the halves of the channel are straight meeting at the center in the sections. In Figures 10 and -11 much the saine cross section, eilectively, is curved. Figure 10 corresponds generally in its operation to 51 and down along'the` edges 50', while the flow in Figurel 11 will be up along edges 50 and down along middle 51.

In Figure 12 the sections of the two channel legs are sloped laterally, being neared at the edges 502, at any given height, than thev are at the edges 512, with the result that the greater ow upwardly will take place at or near the edges 512, and the greater flow downwardly at or near the edges 502.

In Figure 13 a. single staggered lateral channel 38- is shown, differing from the channel 38 in the fact that the cross sections of the channel portions are parallel not only with each other, but witht-he axis of the transformer leg, whereas the cross sections in Figure 1 are at an angle relatively with respect to the axis of the channel leg, tending to increase the amount of flow of: molten metal up that corner of each of the cross sections further from the 'transformer winding and from each other, and down that corner of each of the cross section edges nearer to the transformer winding.

In Figures 14-17 the channels 382 are further from each other at the bottom than at the top, which would cause circulation whether the enclosed winding were used, or

lwith pancake windings 52 ot' which twoare shown in these figures. The pancake windings result 1n a. pressure of a metal toward lll' the space in the centei` upon them, causing the metal to flow upwardly along those sides 53 of the channel toward each other with consequent gravity downward flow of cooler metal along the other sides 54 of the channel.

In Figure 18 the two legs of the secondary channel are of rectangular cross section parallel to the axis of the coil and are not laterally oiset with respect to each other. The alternating current passing through the pancake coils causes upward flow of molten metal along the center lines 54 of these channels with conse nent gravity downward ow of molten meta along the edges'l The formy shown in Figures 19 and 20- enerally corresponds to those shown in 41iguresA 8 and 9, and those in Figures 21 and 22 to the forms shown in Figures 10 and 11, with the differences, however, that the current in the pancake coils causes repulsion of metal to the center and upward liow of metal along the middle, as at 51 and 5l',

\ tention to cover herein all such as come with\` in the reasonable spirit and scope of my inwith downward flow of metal along the outer edges 50 and 50.

Figure 23 corresponds generally with Figure 17 except that the two channels 38 come together at the bath to a single opening on each side.

A single pancake coil only is used in Figure 2li andin Figures 25 and 26, as could be the case in any of the figures. The section in Figure 24 is like that of Figure 19.v The force from the single pancake coil would tend to drive, the molten metal toward 'that edge of the channel furthest from it. Vith slight eccentricity this would mean merely that more metal would go up the leg further from it than the nearer leg, and more metal 'would come down by gravity flow along the nearer leg than that further fromit. If the difference in pressure were lgreat enough this would result in unidirectional flow.

In Figure 25 the general arrangement of channel sections is that of Figure 12, but the single pancake coil would cause molten metal ,to come up the edges of the channel further from the lcoil with gravity flow down along the nearer edges. u f

In Figure 26 the single pancake coil would drive the metal away from the coil, tending to produce uni-directional flow up the leg of the channel further from the pancake coil with gravity'return along the nearer lega In Figure 27 the pancake coil is used with a channel whose lower part is concentric with the coil. As in Figures 15-25 single or double pancake coils could be used.

It will be noted that the crucibles in Figures 14-27 all lack the metallic casing shown in Figures 1-13.

In view of my disclosure herein various other forms will appear to those skilled in the art embodying all or a part of the benefit of my invention. It is, therefore, my invention.

Having thus described my invention, what `I claim as new and desire to secure by Letters Patent is :w p

1. In an electric induction furnace of the submerged resistor type, a channel lresistor unsymmetrical on opposite sides of the secondary having two end connections with the 4furnace staggered laterallyof the winding, a transformer core threading the resistor and a transformer winding upon the core, the current in which exerts different ressur'es upon the twol branches of the resistor at the sani/e heights thereof and causes flow by reason ofthe vlack of symmetry of the secondary. i

2. In an induction furnace having a pool,

a single passage submerged channel .resistor beneath the pool, connecting therewith, a transformer leg threading the resistor and a' winding at some `point upon the leg, the novelty which consists in staggering the entire resistor both axially` and angularly with respect to the coil axis.

3. A furnace having a pool, in combination with walls enclosing a submerged loop resistor for the pool, the horizontal sections of the resistor being concave on one side and l`\convcx on the other.

4. In an induction'furn'ace having a pool, the conbination of walls to enclose a resistor beneath the pool and connecting therewith having, in horizontal sections, yconcave resistor sections facing each other in opposite' legs ofthe resistor, a transformer having a leg interthreading the resistor and a winding upon said leg enclosed'by the resistor.

5p. In an induction furnace, walls forming a pool and a channel beneath the pool having an acute angle at the bottom of the channel and having a channel cross section in horizontal planes concave on one side and con- Vex on the other in combination with a transformer having a leg threaded through the resistor and a winding at some point upon the leg. V

6. In an induction furnace, wallsforming a pool and a channel beneath the pool having an acute angle at the bottom of the channel and a channel cross section in horizontal planes concave on one side and convex on the other, in combination with a tranformer having a leg and Winding threaded through the resistor. f

7. In an induction furnace having a pool, walls forming a channel beneath the pool having an acute angle at the bottom of the channel and a channel cross section/'in hori- 110 zontal planes concave on one side and con-V veX on' the other in combination with a transformer having a leg threaded through the resistor and a winding outside said resistor and adapted to move the metal toward one edge thereof.

8. Anvinduction furnace havin a transformer and a ool and walls orming a te single passage channel beneath the pool for the secondary, the channel having rectangu- 12o lar horizontal channel cross sections in the different parts at an angle with respect to the axis of the transformer winding and to each other, in combination with a transformer leg interthreading the secondary and a Winding on said leg enclosed bythe resistor.

9. An induction furnace havin a transformer and a pool and Walls orming a single passage channel beneath the pool having rectangular horizontal channel cross sections in the different parts at an angle with respect to the aXis of the transformer in combination with a transformer leg intertheading the secondary and a Winding on said leg enclosed by the resistor.

10. An induction furnace having a pool, a transformer having a central leg and a Winding on the leg, in combination with walls forming a single passage resistor channel enclosingr said Winding, the horizontal cross sections of the resistor being longei` in one direction than in the opposite direction and having the longer direction at an angle Wit'h respect to the axis of the. coil.

1l. In an induction 'furnace having a pool, Walls forming a. plurality of channels beneath the pool, a transformer core threaded through said Walls and a pan-cake winding about said core, the channel sloping with respect to the plane of the pan-cake coil.

l2. In an induction furnace having a pool,

Walls forming a channel beneath the pool, a transformer core threaded through said channel and a pan-cake Winding about said `rcore, the channel sloping with respect to the plane of the pan-cake coil.

13. In an induction furnace having a pool, walls forming a channel beneath the pool having in horizontal cross sections the channel sections of opposite resistor legs at an angle to each other, a. transformer core threading the resistor and a pan-cake coil at one side of the channel adapted to press the molten metal to the opposite side thereof. l

14. An induction furnace having pan-cake coil transformer means for circulating molten metal, a pool, and walls forming a resistor channel beneath the pool in Which opposite legs of the channel are staggered with respect to the coil.

EDVIN F. NORTHRUP. 

